1. Technical Field of the Invention
This invention relates to instrumentation for biofeedback of body motion and flexure during kinetic sport activities and for medical monitoring purposes including injury avoidance and rehabilitation. In particular, it relates to a system of body motion and flexure sensors and specialized audible and other biofeedback capabilities, with controllable sensitivity and contemporaneous feedback characteristics, having broad application for monitoring various body movements and joint flexures and capturing or signaling absolute, relational and rotational body motion parameters of distance, velocity and acceleration.
2. Description of Prior Art
Motion sensors for kinetic activities such as golf, tennis and the like have long been known. The use of audible feedback to indicate level of accomplishment to the user via pitch, duration or the modulation of either, are frequently used. For example, Harrison, U.S. Pat. No. 2,064,603 describes an audible metal snap switch in the form of a wrist mounted pressure sensor worn to detect wrist flexure relating to the swing. Pfeiffer, U.S. Pat. No. 3,791,375 describes a sensor attached to a user's foot in order to detect excessive force placed on the foot during motion. Obenauf, U.S. Pat. No. 4,502,035, describes a motion sensor that is mounted to the hat of a golfer for providing audible tones to a headphone worn by the golfer, the tones indicating characteristics of the golfer while swinging the club.
Evans' U.S. Pat. No. 3,270,564, Sep. 6, 1966, is a golf club instrumented to provide an electrical signal which is a continuous function of the motion of the club and an output plot of the resulting motion. Fink's U.S. Pat. No. 3,808,707, May 7, 1974, presents a physical training system that provides an audible signal indicative of an analog of a predetermined physical activity in the manner of a musical metronome. Hammond, U.S. Pat. No. 3,945,646, Mar. 23, 1976, instruments a golf club with multiple accelerometers to indicate the precise position of the golf club at the instance of impact when striking the ball, and introduces the concept of wireless transmission of the data to a remote receiver for analysis and presentation via crt screen and/or printer.
Fletcher, U.S. Pat. No. 3,972,038, Jul. 27, 1976, introduces an accelerometer and telemetering transmission link all of which fit into a ring worn on the finger of the user. Barasch, U.S. Pat. No. 4,094,504, Jun. 13, 1978, places reeds on a tennis racquet to provide an audible tone when wind passes over them. James, U.S. Pat. No. 4,110,918, Sep. 5, 1978, offers a biofeedback training system with portable, self-contained modular units for preprocessing and storing data.
Wilhelmson, U.S. Pat. No. 4,346,363, Aug. 24, 1982, discusses a unit that produces an audible tone where the frequency is a function of the direction of the measured force and the intensity of the sound is proportional to the magnitude of the force. Whiteneir, U.S. Pat. No. 4,660,289, Apr. 28, 1987, senses joint positionwith an indicator that attaches to adjacent body members and measures relative position. Matthews, U.S. Pat. No. 4,867,442, Sep. 19, 1989, discloses a device worn on the head with sensors place about the headband to feed a microcomputer heart rate, time and exercise related inputs.
Smithard, U.S. Pat. No. 4,906,192, Mar. 6, 1990, employs sensing of forces generated at the foot of a boot mounted on a ski, and generates a CRT display of a simulated track that would result from the activity, for training purposes. Wilhlem, U.S. Pat. No. 4,991,850, Feb. 12, 1991, shows an instrumented golf club hardwired to a wrist worn indicating device. The display indicates the characteristics of impact (impact, club acceleration, direction, etc.) as a result of the measurements made during this action.
In general the prior art deals with systems that measure specific actions of an athletic activity. The are implemented in ways that do not lend to generalization (e.g. limited to a specific motion of the head).
Many of the systems provide feedback to a display, or in the case of audio feedback, a single tone or a continuously modulated pitch or duration of the tone is used. In actions that occur quickly, whether they be a fast 0.05 second duration of a baseball swing or a slow 0.25 seconds for a golf swing, tonal feedback does not convey the information in an easily remembered fashion and it is sometimes difficult to figure out just what happened.
Some of the cited inventions work by comparing predetermined stored information to that of the user as a specific tempo. This limits training objectives to third party standards that have no connection or relevance to the user's own unique body characteristics, style, condition and experience.
Some prior innovations are premised upon transmitting information to a base station for processing and display. This is a useful training tool, but it lacks the impact and natural benefit of instant biofeedback that is comparable to the normal response time of the body's own nervous system.
Numerous other kinetic sensors are described in various patents to provide information concerning a user's kinetic activities. While audible feedback has been used, it has largely been to indicate the occurrence of an event, (i.e. your downswing has started, your wrist has flexed properly) rather than to portray a contemporaneous "signature" or feel for the total event. The multiplicity of proposals for such systems, and the limited availability of such systems in the commercial market, demonstrate both the need for a convenient, reasonably priced, general purpose, informationally-useful sensor and biofeedback system, and the apparent difficulty of realizing this goal. The present application is directed to such a system.